Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Assumptions in Newton's Second Law

  1. Sep 17, 2014 #1
    With my understanding of Newton's second -- if I am going to use it to solve a problem, I would need to write ALL velocities in the system with respect to the lab frame (inertial rest frame) -- correct?

    Thanks,
    Chris
     
  2. jcsd
  3. Sep 17, 2014 #2

    A.T.

    User Avatar
    Science Advisor
    Gold Member

    Velocity doesn't even appear in Newton's second law.
     
  4. Sep 17, 2014 #3
    It does in the rocket problem. ##\dot{p}=\dot{m}v+m\dot{v}=F_{thrust}##. Also, if you are calculating the the change in momentum over some time interval ##F=m\frac{\Delta v}{\Delta t}##.

    Chris
     
  5. Sep 17, 2014 #4

    A.T.

    User Avatar
    Science Advisor
    Gold Member

    What, you have there is acceleration and average acceleration, which of course can be expressed in terms of velocity.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Assumptions in Newton's Second Law
  1. Newton's Second Law (Replies: 12)

Loading...